Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates
Zello - Zello's push-to-talk app redefines the walkie talkie. It's a great push-to-talk over cellular (PoC) alternative for businesses and organizations. Learn more about the best walkie talkie app in the market.
MessageBird - Reach 7 billion phones in seconds via SMS, Chat & Voice. Try it for free and improve your communication.
Walkie-Talkie.io - This completely free walkie-talkie app online allows you to communicate quickly and easily with your friends. Go to the same radio frequency, push to talk and that's it! There is also a mobile iOS version and always 100% free !
Plivo - Plivo simplifies your customer engagement.
NuovoTeam - NuovoTeam Push-to-Talk (PTT) App for Frontline Workforce.